Refining of petroleum hydrocarbons



United States Patent REFINHNG Gil PETRULEUM HYDRGCAREBGNd: Peter Thomas White, dunbury-on-Tiiaines, England, as-

signor to The British Petroleum Company Limited,

London. England, a British joint-stock corporation No Drawing. Filed duly 20, 195?, 591. No. 828,011

Claims priority, application Great Bri ain Italy 25, 1958 Claims. (Cl. 208-255) This invention relates to the controlled hydrogenation of gasolines, which tend to form gum, due to the presence of one or more unsaturated hydrocarbon compounds such as styrenes, cyclopentadiene or other conjugated dienes. An example of such a gasoline is steam cracker gasoline which is herein defined as a gasoline produced (by cracking a petroleum hydrocarbon or mixture of hydrocarbons boiling in the gasoline or kerosene boiling range in the presence of steam.

Besides the gum forming compounds the gasolines may also contain other unsaturated compounds such as monoolefins and aromatics. Since these compounds are of relatively high octane number it is undesirable to hydrogenate these compounds more than is necessary to ensure the required improvement in the gum forming tendency, hence the necessity for controlled hydrogenation.

After the hydrogenation it is desirable to rerun the gasolines to remove a small proportion of bottoms, and it has now been discovered that improved results are obtained if the maximum rerunning temperature is kept below a given figure. Accordingly, the present invention consists in a process for the hydrogenation of a gasoline containing gum forming unsaturated hydrocarbons, particularly steam cracker gasoline to reduce the gum forming tendency, in which the products are rerun to remove a small proportion of bottoms at a temperature not eX- ceeding 250 C. Preferably the temperature does not exceed 205 C.

The rerunning preferably eliminates not more than 6% by weight of heavy ends. Since the highest temperature occurs at the base of a distillation column, this is, in practice, the temperature which is kept below 250 C. To assist distillation under these conditions, one or more of the following methods may conveniently be employed: preheating the material passing to the distillation column, distilling in the presence of steam or distilling in the presence of an inert gas such as nitrogen or distilling at pressures below atmospheric pressure during at least the latter part of the rerunning.

The hydrogenation of the gasoline may conveniently be carried out under the following conditions:

Temperature 0 to 200 C. (preferably 80- 180 (1.). Pressure 0 to 1000 p.s.i.g. (prefenably 200-500 p.s.i.g.). Gas rate (including make-up gas) 300 to 2000 s.c.f. hydrogen/b. Space velocity 0.5-10 v./v./hr., preferably about 2 v./v./hr.

The hydrogenating gas which may be used on a once through basis or with recycle, may be pure hydrogen or a gas containing at least 25 mol percent hydrogen, preferably at least 25 mol percent hydrogen. As is well known in the art, severity of hydrogenation can be increased by raising the hydrogen partial pressure, raising the reaction temperature, increasing the hydrogen/feedstock ratio, or decreasing the fiow rate. in general, the hydrogen consumption, which is a measure of the hydrogenation severity, will be at least 60 s.c. f./b., preferably at least s.c.t./b., and it may be more than sci/b. the upper limit being fixed by the undesirability of substantially reducing the octane number of the gasoline by hydrogenation of mono-olefins and/ or aromatics more than is necessary to ensure the required improvement in the gumtorming tendency For certain gasolines an upper limit of 150 sch/b. may be adequate but up to 250 s.c. f./b. may be required in other cases. The research octane numher (with 1.5 ml. TEL/l8) of the product is preferably not more than one number below the octane number of the similarly leaded gasoline feedstock. Leaded research octane numbers are prefeired as a basis for comparison since while there may be some slight drop in research octane numbers (clear) as between feed and product, this is offset in the case of the leaded octane numbers by an increased lead response in the product.

The characteristics of an acceptable commercial gasoline are determined in the long run by its behaviour in use. However, certain tests can be used to give an indication of the behaviour of a gasoline in an engine or during storage.

Suitable tests which give a measure of the gum stability of gasolines during storage or in an engine are the induction period test (ASTM Method 13525-55), the accelerated gum test (10373-49), and the existent gum test (ASTM Method 13381-57).

A particularly suitable hydrogenation process is one using a nickel catalyst, the nickel being supported on a suitable base, for example, activated alumina, a group H metal carbonate such as calcium carbonate, sepiolite or any base which has a low activity for cracking reactions and a low activity for polymerisation reactions. Other examples of such low-activity bases are calcium, barium, strontium, or magnesium oxides, diatornaceous earths, fire brick derived from diatomaceous earth, silicon carbide, quartz, carbon (for example charcoal and graphite), pumice and deactivated alumina. The catalyst preferably contains from 1.0 to 50% of nickel, expressed as elemental nickel by Weight of total catalyst, more particularly 5 to 15% wt.

The nickel catalyst may be prepared by impregnation of the catalyst base with a solution of an easily decomposable nickel salt, e.-g. nitrate, acetate, followed by drying the mixture and roasting at temperatures up to 500 C. for 2 hours.

The catalysts may also be produced by mixing together finely divided nickel compounds, for example n trate, acetate with the catalyst base in finely divided form and pelleting and roasting at temperatures up to 500 C. for 2 hours.

The catalyst may also be prepared using nickel formats, either using the impregnation technique or using the mixing technique. In these cases, it is only necessary to dry the catalyst and no roasting is required.

Before use, the catalyst as prepared above requires activation. This is conveniently carried out by heating the catalyst (eg. in situ in the plant reactor) at 150 to 600 C. in a stream of hydrogen or hydrogen containing gas, at a pressure in the range 0 to 200 p.s.i. g., for up to three days. The temperature is preferably maintained at 200-300 C. and the pressure at atmospheric. When s) the catalyst is prepared from nickel for-mate, activation may be carried out by heating at 150 C.-300 C. in an inert gas stream for a shorter period, preferably about 4 hours. After pretreatment the catalyst must not come into contact with oxygen or any oxygen-containing gases as this will cause deactivation.

The invention will be illustrated with reference to the following examples:

EXAMPLE 1 Two steam cracker gasolines were hydrogenated using a catalyst of 9.35% wt. nickel on alumina under the following process conditions:

Pressure 165 p.s.i.g. Space velocity 2 v./v./hr. Gas recycle rate 580 s.c.f./b. Make-up gas Pure hydrogen.

The treated gasolines were stabilised to remove C and lighter hydrocarbons and then return to remove 4% wt. of heavy ends. The maximum temperature during rerunning was different in each case to demonstrate the effect of the rerunning temperature on the quality of the product. The rerunning at the higher temperature was a normal atmospheric distillation, while at the lower temperature the distillation was carried out in the presence of steam.

Inspection data on the lfeedstocks and the rerun prodnot are given in Table 1 below:

Table 1 Process conditions Feed A Product Feed B Product Temperature, C 150 97 H3 consumption, s.c.f./b 98 61 Heavy ends removed by rerunning at percent wt 4. 3. 1 Base temneratiu-c, 0. 274 217 Spccifie Gravity (60/60 F.) .7990 7900 .7995 Recovered at 70 0 14 14 10 Recovered at 100 0--. 39. 5 40 42. 5 40. 5 Recovered at 140 C 74. 5 7 73. 5 78 Total Sulphur 0.023 0.012 0.012 Bromine Number 53. 8 61. 2 50. 5

Gum Eristent, rug/100 1111. (after washing in n-hcptanc) 4 3 10 2 Gum Accelerated, mg./100 ml. (120 mins.) (after washing in n-heptane). 0 22 10 Induction Period (ruins) 345 190 220 245 ON. (Res. clear) 95. G 04. 0 94.4 O.N.+1.5 ml. TEL/1G 98. 0 97. 4 97. 6

From the table it will be seen that the product from Feed A has worse induction period and accelerated gulm figures than the feed, i.e., the improvement effected by the hydrogenation has been more than outweighed by the rerunning at a temperature of 274 C. On the other hand, Feed B which is worse than Feed A as regards gum and induction period figures has been improved by a hydrogenation to a lower hydrogen consumption than Feed A coupled with a lrerunning at a temperature of 217 C.

EXAMFLE 2 This example shows the advantage of rerunning at a temperature below 205 C.

Two steam cracker gasoiines were hydrogenated using a catalyst of 10% wt. nickel on chalk under the following process conditions:

Pressure 250 pusig.

Space velocity 2 v./v./ hr.

Gas recycle rate 700 s.c.=f./b.

'Make-up gas Platformer gas vuth 76% vol. hydrogen.

The raw products were rerun at two difierent temperatures. One product was rerun under normal atmospheric distillation conditions at a maximum base temperature of 288 C. The other product was rerun by distilling normally to about 50% volume bottoms with a maximum base temp t 0f 50 C. and then steam distilling Table 2 Food Product from Food Product Process conditions A Feed A B from Feed B Temperature, 0 170 160 150 E consumption, s.c. 167 177 170 Heavy ends removed b rcrnnning, percent wt... 3. 6 3. 6 97% vol. overheads Marimum base tcuip., C- 288 288 109 Specific gravity (00/ 00 F. 7880 .7815 7820 .7825 7770 Recovered at 70 0., percent vol 23. 5 21. 5 26 13 11.5 Recovered at 0., porceut vol 53. 5 60 61.5 46 46. 5 Recovered at 0., percent V01 S3. 5 88 S8 83. ii 86. 5 Total Sulphur, percent wt- 0. 012 .008 .007 .000 .008 Bro :ninc Number 50. 6 50. 8 07. 4 4 Gum Eristent, mg/100 ml.

(after washing in n-heptaae) 2 1 1 8 Trace Gum Accelerated (120 min.) m n/100 ml. (after washing in n-heptane) 14 4 8 38 2 Induction Period, ruins..- 25 300 245 270 720 OJN. (Research) Clean. 95 6 94.1 94. 3 93. 2 02. 3 ON. (Research)+1.5 n11.

TEL/1G 90. 2 96. 8 ON. (Rcscarch)+1.8 m1.

TEL/1G 98. 0 98.1 98.6 Lauson rating mg./3.25 080 (after ageing for 20 days at 110 F.) 389 39 A steam cracker gasoline was hydrogenated using a catalyst of 9.15% wt. nickel on alumina under the following process conditions:

Pressure 220 p.s.i.g. Space velocity 2 v./v./hr. Gas recycle rate 1,000 s.c.f./b. Make-up gas Pure hydrogen.

The raw product was rerun by two dilierent methods with maximum base temperatures of 150 C. and 273 C. respectively.

Inspection data on the feedstock and the rerun products are set out in Table 3 below:

Table 3 Process conditions Food Product Temperature, C 150 70 Hz consumption, sci/o 122 122 Heavy ends removed by rerunnmg, percent wt Maximum base temo, 0 Specific gravity (60/00 F.) Recovered at 70 0., percent vol.

Recovered at 100 0., percent vol 82 Recovered at 140 0., percent vol 91. 5 Total Sulphur, percent wt 0.006 Bromine Number 60. 4 Gum Existent, rug/100 m alto: washing in n-hentnue) 3 1 1 Gum Accelerated (120 mm.) mg./100

washing in n-heptane) 15 9 4 Induction Period, mins 245 570 720 O.N. (Research) Clear. 89.7 83.0 O.N. (Research)+1.5 ml. TEL/1G 95.4 95.1

I claim:

1. In a process for the hydrogenation of steam cracker gasoline containing gumforming unsaturated hydrocarbons to reduce the gum-forming tendency of said unsaturated hydrocarbons, the hydrogenation being carried out in the presence of an elemental nickel catalyst on a support at a temperature of between about and 200 C. and a pressure of between about 0 and 1000 p.s. i.g., the improvement which comprises re-running the total gasoline following hydrogenation at a rerun column base temperature sufliciently high to remove not more than 6% by weight of bottoms and recovering, as a product, a rerun gasoline having a lessened gum-forming tendency, said base temperature being controlled and maintained by positive variation rrom normal atmospheric distillation conditions and being below that which, for removal of the same amount of bottoms, would be employed as the base temperature under normal atmospheric conditions to produce a rerun gasoline having a greater gu mform.- ing tendency than the product aforesaid.

2. The process of claim 1 wherein the hydrogen consumption during the hydrogenation step is between about 60 and 250 s.c.f./b.

3. The process of claim 2 wherein the hydro-gen consumption during the hydrogenation step is between about 150 and 250 sci/b.

4. A process as claimed in claim 1 wherein not more than 6% by weight of bottoms is removed.

5. A process as claimed in claim 1 wherein the research octane number (with 1.5 ml. TEL/1G) of the final prodnot is not more than one number below the research octane number (with 1.5 ml. TEL/IG) of the feedstock prior to hydrogenation.

6. A process as claimed in claim 1 wherein the catalyst contains from 1 to oi nickel, expressed as elemental nickel, by weight of total catalyst.

7. A process as claimed in claim 1 wherein the catalyst contains from 5 to 15% of nickel, expressed as elemental nickel, by weight of total catalyst.

8. A process as claimed in claim 1 wherein the rerun column base temperature is -l80 C. and the pressure is 200-500 p.s.i.g.

9. A process as claimed in claim 1 wherein the gas rate during hydrogenation is 0-2000 scff. of hydrogen/ b. and the space velocity is 0.510 v./ v./ hr.

10. A process in accordance with claim 1, wherein the rerun column base temperature does not exceed 205 C. I

References Cited in the file of this patent UNITED STATES PATENTS 2,042,298 Davis May 26, 1936 2,073,578 Guynn Mar. 9, 1937 2,116,061 Dorrer May 3, 1938 2,542,471 Brandon Feb. 20, 1951 2,638,438 Holfman et a1. May 12, 1953 2,735,879 Redcay Feb. 21, 1956 2,865,851 Porter Dec. 23, 1958 2,897,142 Jacobs et a1. July 28, 1959 2,901,423 Herbert et al Aug. 25, 1959 2,922,759 Schlinger Jan. 26, 1960 2,953,521 Bowles Sept. 20, 1960 2,969,316 Stanford et a1. Jan. 24, 1961 3,024,188 Yeo et a1. Mar. 6, 1962 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3 ,113,096 December 3,, 1963 Peter Thomas White It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 63, for "25 mol" read 50 mol column 3 line 19, for "return" read rerun Signed and sealed this 5th day of May 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN A PROCESS FOR THE HYDROGENATION OF STEAM CRACKER GASOLINE CONTAINING GUM-FORMING UNSATURATED HYDROCARBONS TO REDUCE THE GUM-FORMING TENDENCY OF SAID UNSATUATED HYDROCARBONS, THE HYDROGENATION BEING CARRIED OUT IN THE PRESENCE OF AN ELEMENTAL NICKEL CATALYST ON A SUPPORT AT A TEMPERATURE OF BETWEEN ABOUT 0 AND 200*C. AND A PRESSURE OF BETWEEN ABOUT 0 AND 100 P.S.I.G., THE IMPROVEMENT WHICH COMPRISES RE-RUNNING THE TOTAL GASOLINE FOLLOWING HYDROGENATION AS A RERUN COLUMN BASE TEMPERATURE SUFFICIENTLY HIGH TO REMOVE NOT MORE THAN 6% BY WEIGHT OF BOTTOMS AND RECOVERING, AS A PRODUCT, A RERUN GASOLINE HAVING A LESSENED GUM-FORMING TENDENCY, SAID BASE TEMPERATURE BEING CONTROLLED AND MAINTAINED BY POSITIVE VARIATION FROM NORMAL ATMOSPHERIC DISTILLATION CONDITIONS AND BEING BELOW THAT WHICH, FOR REMOVAL OF THE SAME AMOUNT OF BOTTOMS, WOULD BE EMPLOYED AS THE BASE TEMPERATURE UNDER NORMAL ATMOSPHERIC CONDITIONS TO PROUDUCE A RERUN GASOLINE HAVING A GREATER GUM-FORMING TENDENCY THAN THE PRODUCT AFORESAID. 